There is a shuttle that goes from Terminal F to Terminal A and takes about 10 minutes. If everything goes perfectly, you should be able to make the connection, but personally I would look for an alternative flight that gave me at least 90 minutes (preferably 2 hours) to connect given that missing your int'l connection would probably result in an overnight in Philly and rebooking subject to availability the next day being even harder traveling in a group of 3.